Actually I had a Join/Part flood protection that disables these events, since my connection isnt that fast and I get lagged when it happens. I belive I've asked for some help in this forum too, and I think you were one of the posters...
The thing is that, at least in my script, the ! suffix did not stopped the events, while putting the 'haltdef' did, so I just copied from my mIRC and pasted here..
I've just tested it again, and it still doesnt work
Maybe the ! not working is a bug?
